The Baltimore Longitudinal Study of Aging (BLSA) is a major research resource for scientists doing work in the field of Gerontology. It provides a well-described group of men and women between 20 and 96 years of age for studies of the mechanisms of human aging. Currently some 50 projects in physiology, biochemistry, psychology, nutrition, pharmacology, endocrinology, and genetics, are in progress, being carried out by intramural scientists in 11 sections of 8 different laboratories.